The feasibility of identifying myocardial ischemia and infarction through the measurement of changes in left ventricular wall motion will be assessed in man. An electronically steered real-time, two-dimensional phased array echocardiographic scanning system with modern signal and data processing techniques are to be employed. We will evaluate the echocardiographic scanning system (Varian) in terms of a) image quality, distinctness of borders, and the proportion of left ventricular endocardium and epicardium visualizable, and b) develop techniques which will permit acquisition and processing of quantitative information on motion of the left ventricular endo- and epicardium. Initially this will involve manual tracking techniques. Later efforts will be directed toward partial automation of data acquisition. Also we will use conventional M-mode echocardiography to compare several echo-detectable wall motion abnormalities for sensitivity and specificity in detection of myocardial ischemia and infarction. These studies will include determination of time course of changes in regional wall motion during development of ischemia with atrial pacing or exercise. A number of parameters of wall motion and thickening which reflect rate of ventricular relaxation as well as contraction will be studied. Subsequently the clinical value of the phased array two-dimensional echocardiographic system will be assessed in comparison to conventional echocardiography and localizing and quantifying extent of wall motion abnormalities in patients with ischemic heart disease. Finally we will evaluate the echocardiographic localization of ischemic and infarcted myocardium against information obtained from pathological studies, exercise stress testing, thallium 201 myocardial perfusion scanning, and coronary arteriography and left ventriculography.